2003 diesel 5.9 wont start unless I plug the heater in
 

It started this back in December. The truck only has 109,000 miles on it! Now when it's 50 degrees I still need to plug the thing in! It takes all day sometimes to get it to start even when plugged in. When it starts it runs great, gets 21-26 mpg on the overhead, uses no fluids and doesn't smoke. I see other threads where they claim it's the injectors, cracked fuel line, or this and that but I can't find 1 post that has the answer or a follow up on the cure! I hate the thought of putting in injectors at 3,000 bucks when it could be a simple fix. Thanks in advance for your help!
Anyone looking for a nice low miles cummins that won't start?

Is the grid heater working properly?

bftrain.....I'm so stupid when it comes to a diesel, I know nothing other than to wait til the idiot light goes out to turn the key! WHAT IS THE GRID HEATER AND HOW DO I KNOW IF IT'S WORKING? Is that what you all call a glow plug?
What I did notice is this morning at 40 degrees I turned the key on and I didn't hear the dddddddddt noise ( I always thought was a fuel pump) under the hood prior to attempting to start it. It did not start so I plugged it in for about 3 hours. When I tried it again I heard the normal ddddddddddddt, the start light on the dash went out and it started without any problem! This is the scenario I've been going through all winter. It won't start unless I plug it in. It's like there is a bad censor some where??? If it is below 20 degrees I may need to plug it in overnight!
What I don't understand is why would plugging it in help to start it if the injectors were bad? I don't understand the relationship between the two! If it's something simple to fix I'd keep the truck. If not, she's gone! I had a warranty (the chrysler warranty and aftermarket) on it up to 100,000 miles so I was well covered and at 109,000 this crap happens. My luck!

I want to ad that I did change the fuel filter and I ran injector cleaner through it, no help there.
I also did the key on off 3 times and saw this P0336 and it then said done Does that help to tell anyone what may be wrong?

That code is for the crank sensor circuit. You might try unplugging and cleaning the connection next step would be to change the sensor.

Temperature can mess with electrical connections it was doing it on my 07's valve cover gasket I would get random injector group b problems and tracked it the weather-pack connector on the valve cover gasket.

I was not trying to be an a$$ or pick on your intelligence. Just because there is a noise the relay is closing does not in any way mean the heater is getting hot. I was just trying to get all the info, I have seen many simple things get overlooked by even the most experienced techs :argh: myself included.

Also. http://www.cumminsforum.com/forum/3r...s-plugged.html

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Also. Won't start when cold unless plugged in. Help pls - Page 2 - Dodge Cummins Diesel Forum

Oh I know you were only trying to get info and I wasn't even thinking you were being an a$$! I really do appreciate your input!
I see where this is sometimes a crank sensor issue in other posts! You may be onto something here and with a little luck may have saved be 3 grand over doing an injector system! So, can you guide me to where this crank sensor is at? Remember, I know very little about these diesels....THANKS IN ADVANCE!:c:

A video about 1:06 he shows the sensor.
The position is about the same all years.